The Achilles tendon is a tendon that attaches your calf muscle to your heel bone (calcaneus) and is the largest and strongest tendon in the human body – taking more force than any other joint, muscle, or tendon. The Achilles tendon allows you to move forward from standing and comes into play whenever you’re accelerating, changing direction, or coming to a halt.
In extreme cases the result can be a rupture, usually at the point where the tendon attaches to the calcaneus. This can be a partial tear, where some of the fibres of the tendon get torn, or a complete tear, where the entire tendon comes away from the heel bone. In some cases, this also causes an allusion fracture where pieces of calcaneus bone break away along with the tendon.